What is Buoyancy Effect of TGA experiment?
TGA (thermogravimetric analysis) is an important method to analyze the hydration products of cementitious materials. When a TGA test for cementitious materials sample is performed, the initial TGA curve may appears as such:
As material researchers, we know density is the physical property of materials. Even since grade school, we are taught that density is simply the mass of an object divided by its volume.
However, this is pretty complicated in the case of cementitious materials. The mass of a certain amount of harden cement (or concrete) paste is a finite value, but how about the volume? since the harden cement paste is porous, how do we consider the open and close pores inside the paste as we want to determine the volume?
Theoretical background: see chapters 3 and 4 in Machiels (2010). Sample preparation method modified from Machiels et al. (2008).
Representative sampling
The mineralogy and glass content of slags depend largely on the mode of cooling of the slags, e.g. slow cooling in a slag pot can result in a large amount of crystalline phases, and fast granulation in water can result in high glass content. A mineralogical analysis will thus only represent the mineralogy of a slag system for a certain grade of cooling and strongly different results can be obtained when cooling conditions are different between the different batches.
Even in a single slag pot, mineralogy and glass content can vary strongly. Taking a sample representative for a slag pot can be done by performing the sampling after a first size reduction of the bulk material or, by mixing representative parts of the slag pot (sides of the pot, center, near cracks, in center of slags, etc.)
Construction industry, the only industry still does things manually.
Even in the 21st century, to build a house right now is still a slow, labour-intensive, dangerous process, and almost always over-budget. Unlike the motoring or technology industries which use automated production methods to complete routine construction tasks, housing construction is one of the only industry that still does things manually till now, as said by Professor Khoshnevis from USC.
Among the conferences taking place every year on cement science, International Congress of Cement Chemistry (ICCC) is almost the most important one. The conference takes place every four years. The latest one is the 13th ICCC hosted in Madrid Spain in 2011 and the next one 14th ICCC will be hosted in Beijing in 2015. During the 13th ICCC, there were more than 900 participants from over 60 countries all over the world, received more than 400 papers on cement science, which cover 9 subjects: